Venetian blind



July 29, 1952 F. GRlEssER 2,604,939

- VENETIAN BLIND Filed Sept. 27, 1950 5 Sheets-Sheet 1 ,7 zf f V 9 5 l 95 EVE? 10 7; ,w

F si E2 #12J E -l 59 u z L 27 'A 5 f7 25; 33 37 77 32 a w/ f f y 3 35 43 7 w JW W W -7 23 74 1X X f5 22' 23 7/ 30 7/ JPL f a' 2f', 72 J0 2.: -27 59 j w W m4 23] .l 22

July 29, 1952 F. GRn-:SSER 2,604,939

VENETIAN BLIND Filed Sept. 27, 1950 5 Sheets-Sheet 2 /NVENTRI Fml @MESSER Mmmm ,km @Mm Hmmy Filed'Svept. 27, 1950 I A 5 Sheets-Sheet 3 July .29, 1952 F. GRn-:ssen 2,604,939

- VENETIAN BLIND NVENTOR.'

Emu CTRESsER u MwsmLLwduvmg/a F. GRIESSER VENETIAN BLIND Jgly 29, 1952 Filed Sept. 27, 1950 5 Sheets-Sheet 4 rml. VP mmm ER R @im F. GRIESSER VENETIAN BLIND July 29, 1952 5 Sheets-Sheet 5 Filed Sept. 27, 1950 ff 73/ zz.

Hman Ey@ also pivotally mounted on shaft 2. Two chains I6 and II are suspended on each of the diametrically opposed pins 8, the lower end of each chain being connected to one of the lath supporting bands I2 or I3 (Fig. 4). The chains extend through transversal slots I5 in the bottom of the casing -I. A spiral spring I6 wound around shaft 2 has one end abutting against the casing I, while the other end acts against one arm 9, thereby continuously applying a torque on the two swing frames 1, 8, 9 which are rigidly interconnected by the sleeve 6, and are thus applied against a fixed abutment I1 carried by the casing I.

Between the two arms 'I and 9 of each swing frame a winding roll of drum I6 is mounted on the shaft 2, and rigidly connected with thev shaft by a set screw I9 (Fig. 5). The drum I8 is provided with a peripheral groove 26. On the bottom of the groove at 2i is fastened one end of a steel tape 22, which can be wound up around the drum; The steel tape extendsidownwardly .betweentwo guide rolls 23 which are disposed in an opening of the bottomof the casing, and traverses a slot 24'providedjin each lath I4, and is Y attached to the lowermost lath in known manner.

In a radial opening 25 of the drum I8 is lodged a spiral spring 2S bearing, by its inner end on the shaft 2, while the outer end acts against a pin 21, which is radially movable in slots 26 Aof the drum I8. The pin 21 carries two bolts l29 Vwhich are located within the circumference of the drum I8 when the spring 26 is compressed, as shown in Fig. 5. The pin 21 is normally maintained by the wound up steel tape against the inner end of the slot 28, and the spring 26 is compressed. Only'in case the blind is completely lowered and the steel tape fully unwound, the pin 21 is released by the steel tape andthe spring 29 then urges the pin 21 outwardly against the outer end of the slots 28 into the position shown in Fig. v6; the bolts associated with the pin 21 also move outwardly and4 extend now beyond the circumference of the drum rI 6.

Fig. 4 shows the position of one of the swing K frames when the blind is partially lowered. The

bolts A29 are locked within the circumference `of the drum I8, and as the steel tape partly is wound up on the drum, the pin 21 which carries the bolts is held against the inner ends of the radial slots 28 by the tape 22. Owing to the spiral spring I6 (Figs. l and 2) theswing'frame 1, 8,- 9 is maintained in the position shown in Fig. 4. The laths I4 which are carried by the cross straps 30 of the supporting bands I2 and I3 are held in a downwardly and inwardly inclined position, the left side of the laths in Fig. 4 and in Figs. 6 to 12 representing the outer side of the window. When the gear A and the shaft 2 is turned further in the direction of the arrow a, until the laths reach their lowermost end position, as indicated in Fig. 6, the steel tape 22 is yso far unwound from the drum I8 that the pin 21 is released from the tape. The bolts 29 are now in the shown position and project beyond the circumference of the drum I8. The arms 1 are still in the same position as shown in Fig. 4, in which position the spring I6 tends to maintain it. When now the shaft 2 is turned further, the bolts 29 will engage the lower pin 8 and will impart rotation to the swing frame 1, 8, 9 as a whole around the vaxis of shaft 2 against the action of the spring IB. When the arms 1 and 9 reach their horizontal position as shown in Fig. '1, the chain I0 has been lowered and the chain II raised, Aand the lath supporting tapes I2 and I3 have been correspondingly lowered and raised, the cross straps 39 having thus been brought to a horizontal position, so that the laths IB also assume their horizontal or normally open position. When the shaft 2 is turned further in the same direction (arrow a),v the swing frame 1, B, 9 iinallyreaches the position shown in Fig. 8, where one ofthe arms-f1abutsvagainstthe fixed stop I1, so that the shaft 2 can no longer be turned. The laths I4 have now reached their correct closing position, being downwardly inclined from the inner side towards the outer side of the window.

The swing frame1, 8, 9 remains in any intermediate position between the positions according to Fig. 6 and Fig. 8, into which it can be swung by actuation of the gear 4, because the friction clutch `5 prevents any rotation of the shaft 2 in a direction opposed to the arrow a, so that the laths 'may occupy any intermediate position between the end positions shown in Fig. 6 and Figs. t l

In the position according to-Fig.'8 therarm 1 of the swing frame abuts against the fixed stop I1 and prevents further rotation of the winding shaft in the direction of the arrow a. which would cause a raising of the blindv in the wrong direction of rotation of thesl'laft;` -In order to raise the blind it is necessar'yito rotate thev winding shaft 2 in the opposite direction, the steel tape 22 thus being wound up onthe drum YI3 in the correct direction of rotation;

When the blind shall be rais d from the position shown in Fig. 7 or Fig'. 8',f. e.=the blind shall be opened, the gear 4 will beactuated in opposite direction and the sha'ft12 will turn in a direction opposite to the arrow a. The-swing frame 1, 8, 9 also rotates in opposite direction vas --a result of the action of spring IIi,-` and the laths turn from the position shown inl Fig. 8 over' the position shownvin Fig. 7 to the .pos'itionshown in Fig. 6. The frame 1, 8, 9 thenremains in theposition according `to Fig. 6 as it' abuts against thel stop I1. When now the drumfISvalso rotates from the position of Fig. 6 'clockwise direction, the pin 21 which carries the bolts 29is pressed radially inwardly by the tape 22v and the bolts are pushed back into the position according to Fig. 4. The

steel tape which is winding up on the drum I8 pulls the lathsupwardlyf into raised position as shown in Fig. Land'when the gear-'4 is no longer actuated, the shaft 2j is automatically locked owing tothe action ofthe friction clutch 5.

Itwiu be observeatnat the bolts 29 of the Winding'drum` I8, -which'in fully lowered position of the blind engage one ofthe pins 8 of the swing frame, only permit adjusting'of the laths I4 when the -blind is fully lowered. In order to enable adjustment-of the positionof the laths also in any`intermediatelposition" ofV the blind between fully lowered aridffully raisedposition, provision of aV mechanism wl'iic'h'will now be described has beenrnade.e 5 "j As shown innige. 3 and 9; iq fame shaft 2 carries a cam 3l disposed-latera-lly"of:one of the swing frames 1, 8, 9, the camgb'eing v'formed on a sleeve 32 fixed to the's'haft- 2--byfasetvscrew 33. Twoannular discs 34 `andd'i-'f'are rigidly connected with the arm 9 of the` swing frame by means of rivetsV or'screwsiifn pawl 38l is pivotally mountedon a v31j carried by the annular discs 34 and 35, one end 39 ofthe v'pawl'coacting with the cam 3|. l'IhepinV `l'which carries the alcoigeoe 15 une t the pressure;ofthispringi l 6 it remaintained in a'psitionaccordingto'Fig; 4'or Fig. 6, this'pin'i'slocated 'above' the' 'shaft 2',Sasshown in Figs. 9 andl 10. The 'end 39 of' the'pawl is Y rheavier than th'eend 44 of' thepawl, so that f the position of' Figs. 9`and 10'the end 39"`of the pawl owing to "itsweightrestsiori"thecircum ference of the cam 3|. v K v The cam 3l is 'providedfwith arecess' lland a notch 4l separated from-each other' by a' nose 32.

d and up tothe nose`li2.V In-case'the shaft 2' is turned rapidly andthe laths are'uuickly lowered into their lowermost position,"the"endv39"of the .pawl will jump over the notch 4| and arrivesfrom the .nosel 42 immediately' on tothe circular circumference again of the cam and the blind normally lowers into its lowermost position, as has been described by reference to' Figs. 4 and- 6, at v.each revolution of shaft 2 and cam 3l the end 39 e of the pawl jumping over the notch 4l without falling into it. v

When, however, the shaft 2 andthe carn 3l turn slowly in the direction of the-arrow a' the end 33 of the pawlafter passing-the nose 42,

engages with the notch 4I ofthe cam as shown in Fig. the turning cam transmits the move- -ment of rotation to the paw138 and as the pawl is secured to the'swing frame 7, 8, 9, this latter is also turned. In the position according to Fig. 11,

- the` arms 'l and 9 of the swing frame have been turned into their horizontal-position, corresponding to the open ypositionl ofthe laths Hl. The

` blind may remain with the laths in this position,

- tion of the swing frame and a corresponding rotaf tion of the shaft in the direction opposite tothel the friction clutch 5 preventing a backward rotaarrow a. When the shaft 2 is further turned until the position according to Fig. l2, the cam 3i will have turned the pawl38 and the swing frame l, `8, 3 so far, that the laths I4 have reached their main in this position, the friction' clutch 5 preventing a rotation in the opposite direction, and the end 39 ofthe pawl cannot disengage from the cam notch 4l. When, however, the shaft 2 is now turnedl further in the direction of the arl' row das shown in Fig. 12, the backward end 44 clined'surfacecauses the end 44 of the fpawl to` move radially inwards;` the pawll is' pivoted* of the pawl arrives into contact with an inclined surface d3 provided `in the-casing l. This inaround'its'journal `3'1- and the opposite end. 39 of the pawl will disengage from the notch 4I of the i cam. `Owin`g to the action of the spring I6 (Fig.

l) the released swing frame 1, 3, 9-tcgether with the pawl 38 is swung back into the. position according to Fig. 9, and alsothe-laths I4 will returnagain to the position shown in Fig. 9. By further turning the shaft 2 the blind may further i be lowered, and when thenotch 4l -f again engages with the end 39 of the pawl, the already described operation of swingingm'ovementfofthe'pivoted frame l', 8, 9 is repeated once upon each revolution of the shaft 2 on the cam 3|.` Accordingly, in a number of intermediary positions'between `Mfully` raised and fully lowered position of the '-.blind, the lathsrnay be broughtinto'their hori- 5 zontal or'any inclined position.

It has been seen that in the described'Venetian "blind, bythe soleactuation. of thefdrivemeans.4

-may alsof be *adjustedinto their Ahorizontal-or any inclined position;there-areno additional draw cordsrequiredf; 1-bylfrneansi/` of-which' the Ylaths up to now -h'ave'-beenl adjusted -intotheir 'opened or'clofsed positions. e

fFigs. 13 to lshow'af'rnodiiiedr arrangement of a` Venetianbli'nd: operating 'mechanisrn." In 'orderto raise and to'lowerthe 'laths le a cord'or i a cable 45 is used instead of a steel tapef As this cable due to its thickness can notbe wound up in superposed layers as' in the 'case' of a thin steel e tape, a 'long'druin dwi'llbefused forfwinding 'up the cord, this drumfbeing of suchaxialf length, l'that when the blind is fullyraised, -th'e cord-'or A'cable is wound on thev drum surface'in a'single layer of adjacent spiral'windings.` Thev drum' rotates with thewinding shaft`2 and at both ends Ait is secured against axial' movement by a 'sleeve 4l which is clampedto the shaft 2. The'rst .cable winding is 'guided on'the drum vby 'a helical groove lkwhichprevents a's'lipping' of the cable over the edge ofV the drum.' AOne end` of shaft 2 is provided with ascrew'thread 48 and-carried 'by a bearing formed'as a threaded nutsil. f When the shaft 2 isturned, it screws into the nut and accordingly 'is iaxially'displaced 'and the 'drum which simultaneously rotates with the shaft also is 'axially moved.' 'The cable 45, according tothe direction'of` rotation ofthe drum,'is" unwound from the drum" or woun'd'up on the drum,whereby'thecable depending from' the drumk and having-its lower endlattac'hed tothe lowermost lath, remains in thesametransverse vertical'plane,

Y the. laths lonly `being 'moved'fvertically'up and normal' closing position. The blind' also-can re""`4.5

down. The end of shaft v2opp`ositetofthe'threaded end 48 and which is fnotshown, is 'coupled'with a gear as in the ''rst example (Fig.'1), the coupling of .shaft 2 withthe gear'being'formed in such a way that the/sh'aftduring its axial displacement fccntinuo'usly remains in' driving engagement with the gear.

j- A sleeve 6 on the shaft '2j again connects the two swing frames l, 8, -9 serving to' suspend the chains of -the lath supporting tapes, Vwhich "however Aare not shown, only one of the'two'swing frames has been shown. .M .The spiral springVL I6 'which is wound around the sleeve 6 act'sagainst the 'arm ofthe frame and tends tchold the frame in' the position shown` in Fig 15." For the adjustment of the laths thedrums-ji are constructed in the same wayas thedrums I8 of'liigs. 4 and 6.V Two bclts'29 are connected lwith the pin 21, which is slideably arranged in a radial slot'28` of the drum 46. TheL bolts 29'. alscare movablein radial slits and the spring 26 which acts on thepin'Zl tends :to pushthe bolts out ofthe drum..H However, as long as the cable 55 is wound upinthe helical groove 50, the boltsd23, bymeansof the cable l5 which passes over a pin 5I carried by the bolts, are retained in the interior of the drum.. As soon as the laths'A have reached their lowermost posi- Ttion, as shown in Fig;v 15,-the bolts 29 are released from the-cableL and are pushed out of thedrum by the springf 26. By-furtherturning thelshaft i 2 the bolts engagewith the pin Boff theswing frame and turn this latter, whereby the laths It :are brought into their-open position,lor into the closed position as-showninFig. 16. In this position the arm 'I abuts against the stoppin l1 secured to the casing thereby preventing a fur- -`ther rotation ofthe shaft 2. Raising of the -blind therefore cannot 'be-f accomplishedinthe wrong '-wdirection of rotation offthe-shaft 2;fbvut=the .op-

7 to-turn the shaft 2 in the opposite direction in order to raise the laths. y

In order to be able to adjust the laths also in intermediate positions between the raised and the lowered position of theI blind, a drum shaped cam 3| is fixed to the'shaft 2, the cam profile over the length of the drum being similar to that of the cam 3| in Figs. 9'to 12. This cam turns together with the shaft 2 and also takes part in its axial movement. Two discs 34 and 35 are welded to the longitudinalpins 8 of the swing frame, these discs carrying a pivoted pawl 38 similar to that shown in Figs. 3 and 9 to 12. This pawl cooperates with the cam 3| in the same manner as had been described with reference to Figs. 9 to 12; upon each revolution of the shaft 2, when the blind is slowly lowered, the cam 3| over part of one revolution, turns vtogether with the shaft and causes the frame 8, 9, to pivot, to thereby adjust the laths to the desired position, until a further rotation of the shaft 2 causes the pawl to engage the inclined surface 43, which produces the release of the pawl, from the cam 3|' and the return of the frame 1. 8, 9 into its normal position as shown in Fig. 15, by the action of spring I6. The cam 3| alsotakes part in the 'axial movement of the shaft 2, and during the lowering or raising of the blind, the cam moves across the rings 34 and 35, the pawl 38 being continuously in engagement with the cam.

In the modification illustrated in Figs. 17 to 20, again indicates a casing in which the winding shaft 2 is located. According to Figs. 1'! and 19 one end of the shaft 2 is formed with a square end engaged in a corresponding axially extending square socket of a shaft -63 carrying a winding drum 64 for a draw tape 65. 'Io the frame part 6B of a two part window frame 68, E'I are secured steel sheets 88, 09 which carry the drum shaft 63 and also the winding shaft 2. The shaft 2 carries a rotatable sleeve 10 guided by brackets and having on both ends rigid arms 12. Each arm 12 is rigidly connected by two pins 'I3 which are symmetrically located, with respect to the shaft 2 with a second arm 14; the arm 12, pin 13 and arm 14 form together a swing frame as in the previous examples, the two swing frames being rigidly connected by the sleeve I0. Two chains 15 and 'I6 are suspended from each pin 13, on the lower ends of which chains the lath carrier bands 'Il' and 18 being xed. The chains extend through transversal slots 80 in the bottom of the casing I. Two springs 8| and 82 which are wound around the shaft 2 or the sleeve 10 bear with one of their ends against xed brackets 'H and with the other end act against the arms 'I4 or l2, so as to continuously exert pressure on the swing frames 12, '13, 'M and tend to apply them against the xed abutments 83.

Between the two arms 'I2 and 14 of each swing frame is disposed a winding drum 84 secured to shaft 2 by means of a set screw 85. The drum 84 is provided with a peripheral groove 86, on the bottom of which the end of a steel tape 8l is fastened, which tape can be wound up around the drum 04 by rotation of the shaft 2. The steel tape 8T passes through the bottom of the casing I and through a slot in each lath i9 in order to be attached to the lowermost lath in known manner.

As may readily be seen in Figs. 18 and 20, the left hand end of shaft 2 is provided over a certain length with a screw thread 88 and is rotatably mounted in an end ange 89 of the is wound upon the drum 64 according to Fig.

25, the end of the tape passing over a guide roll 95 to the inner side of the window frame, where it will be held in a usual clamping device at the lower part of the frame. The blind can be lowered when loosening this clamping device, i. e. when releasing the drawtape 65, under the action of the weight of the laths, the draw tape being wound up on the drum 64 when the blind is solowered.

In order to adjust the position of the laths 'I9 in any intermediate position of the blind between a fully lowered and a fully raised position, a pawl and ratchet device is provided in the casing I.

According to Figs. 17 and 19 a connecting disc S6 is secured to the arm 'I4 of the corresponding swing frame, and carries two annular discs S8 and 0S connected to each other by pins 9i. A pawl |0| is pivotally mounted on a pin |00 carried by the discs 03 and 99. The shaft 2 furthermore carries a cam disc |02 between the annular discs 93 and 99, the cam disc being provided with two diametrically opposed recesses |03 and two diametrically opposed notches |04, separated by each other by a nose |05 (Figs. 21 to 24). The end |05 of the pawl |L0| is coacting with the cam disc |02. A release abutment |00 is provided in the casing I having an inclined face |09 situated in the path or" the end |01 -of the pawl.

The operation of the described pawl device is as follows: Assuming that the blind is in its completely raised end position and shall be lowered by releasing the draw tape B5. Owing to the weight of the laths the winding shaft 2 -turns in counterclockwise direction (Figs. 2l

to 24), and the steel tape 87 unwinds from the drum 84. The end |06 of the pawl then slides Ythrough the notch |04 (Fig. 21), over the nose |65 and through the recess |03, and arrives on the circular peripheral part of the rotating cam disc |02 without causing a movement of rotation of the pawl |0I. The blind thus may be lowered until its lowermost position, without the laths 19 being affected by this movement of the cam |02; the laths during lowering of the blind reymain in their normally closed position (Figs. 21

and 22), in which they are kept by the swing frame 12, 13, 74, which is subjected to the action of spring 82.

When the blind is to be raised, the shaft 2 is turned in clockwise direction by exerting a pull on the draw tape 05 to unwind it from the drum 04. When the shaft 2 is rapidly turned, i. e. the blind will quickly be raised, the end |06 of the pawl jumps over the notches |04 in the cam |02 and pass from the nose |05 immediately to the successive circular peripheral part of the cam. The blind can thus be completely r'raised without the cam causing any adjusting movement of the laths, since the pawl is not engaged by the cam.

When, however, the shaft I2 and the cam disc |02 will be turned slowly in clockwise direction Figs...21 io.2a..,theei1afn. of. the .pawl .after B WiILenease Withithe.

passna-9venfthel-n0 corresponding-.poten .l Q4. of the; cannidisc p l @2' as .shown .in Fiat- ..1.Th.e1t0tating.cam .disc !GZ now. transmits' the movement iof rotation, to the pawll I and sinthislatter isrigidly connected witnthe swing frame .12',j13; 14, this frame will turn in clockwisedirection against the action of the4 springtl; In thefpositionshown in lig. 23

the swing. fra1ne arms l2, 14 have lreached theirm horiZontal.positio`r1,-. andthelathsjl have been. movedfrom closed toppen, position. The blind maybe left. in this position, since. the draw tape 65, maintained by..itsclamping device prevents a return ,movement ofthe swing frame anda corresponding rotation of shaft. 2 in counterclock.-

wise direction. When,. however, the` shaft 2 is further. turned4 in clockwise direction by pulling clamped. When now the shaft 2 is turned further in clockwise direction, the end |01 of the pawl Il engages withthe inclined face'l of the release abutment-l t8. This inclined face H39 presses the end lill'- of the pawl radially inwards, the pawl IBI rocks about its pivot pin |09 and the opposite end` IE6 ofthe pawl disengages from the. notch |64 of the v cam disc HB2. The released swing` frame 72, i3, lli together with the pawl now swings back under the action of springs 3l or B2 into the position shown in Fig. 21 Where the laths 19 are in their normally closed position.

It results from the above description that adjustment of the position of the laths 'I9 can only be eifected when the blind is raised, but such adjustment can be obtained in any position of the blind between the fully lowered and the fully raised position. The described blind accordingh7 is lowered under the action of its weight when the tape 55 is released, and is raised by unwinding quickly the draw tape 65, While by slowly unwinding the tape, the position of the laths '.'9 may be adjusted.

It results from the drawing, that the blind is arranged between the glass plates a and b of a dou-ble window, the winding shaft 2 having its square end l i8 carried by and removably coupled with the tape drum shaft 63 aligned with the winding shaft 2. The driving mechanism and the laths may be mounted in the casing l itself carried by the two part .window frame 66, S1, independently of the fixed window frame c (Figs. 17 to 20). The whole blind assembly may be mounted in the window frame 66, El and then the glass plates are nxed in the frame and afterwards the complete window with the built in blind mounted in the iiXed frame c. The described blind accordingly can be advantageously used for pivoting windows. The square end Hi of the drum shaft 53 serves for the purpose of adjusting the driving members when the blind is being assembled, and before the window frame 66, Si is mounted into the xed frame c.

Adjustment of the laths into the desired position is effected by actuating the drive members serving to lower and to raise the blind, that is in the previous case the draw tape 65, and no additional lath operating means, as for example a draw cord or the like is required.

I claim:

1. A Venetian blind having a lath operating shaft, winding drums on said shaft, a flexible steel tape depending from each winding-"drum andex-;

tending through the laths and attaeliled tolthey lowerrnost lath, swingl frames looselymounte'd-on A saidoperating shaft, a pair of lathj'carryinggladder bands `dependingfrom each swing frame, a

coupling deyice for; temporarilyconnejcting the swing framesfonrotation withfthe'shafnfsaid coupling devicec omprising'slidable 'bfol12s-mounted l within saidgwindiri drums andfmairitained'e inoperativeA positioi wound up on medium, .anidspririeineans' urei'risfl said bolts out ofthe windingjdruln into u coupling position .when the.. blind.. is lowered. andthe. tape.

unwoundfrom the wind..1 1 g drum.

2. A Venetianublind haring a lath. operating Swine.frames.loosely-carried bys'aidlshait. 'erigir of lath carryingladde'rbands dependingfrom each swing frame,l a'xed abutment for limiting the pivotingmovement of the swingfframesen. the operating shaft. springmeans acting ,onsiaid swing frames. to. maintain the.frain s applied. against said fixedabutment, la kearn disc hiredto the oper-ating shaft, Vsaid carndi'schaving on the periphery thereof, a projectionfa notch and,

a circular surface portioninsuccessive.order, a pawl pivotally' mounted on one of said Swing frames and cooperating with said cam disc, one end of said pawl being heavier than the other end thereof, said projection on said cam disc engaging the heavier end of the pawl to turn said pawl with the cam disc upon rotation of the shaft to turn said swing frames together with the shaft against the action of said spring means and move said ladder bands for adjusting the position of the laths, an inclined surface positioned in proximity to said cam disc, the lighter end of said pawl coacting with said inclined surface and for releasing said pawl from engagement with said cam disc after a predetermined angular movementof said swing frames.

3. A Venetian blind having a rotatable operating shaft, winding drums on said shaft, a nexible pull member on each winding drum, a series of laths operable to be lowered and raised and to be adjusted into horizontal or inclined position, swing frames pivotally mounted on said operating shaft, a pair of lath supporting ladder bands depending from each swing frame, said pull members being adapted to be wound on or off said winding drums to raise or lower said laths, driving means for rotating said operating shaft, and coupling means on said shaft adapted to connect said swing frames for rotation with the operating shaft, said coupling means becoming automatically operative upon slow rotation of the shaft but remaining inoperative upon rapid rotation of the shaft, the same driving means being operative to raise and lower the blind and to adjust the lath position, said operating shaft having a screw threaded end portion engaged in a nut, said shaft being axially moved upon rotation thereof by coaction of the threads and nut whereby said iexible pull member is wound up in adjacent layers on said winding drum. Y

4. A Venetian blind as claimed in claim 3, wherein one end of said operating shaft is coupled to -a driving gear transmitting driving motion 11 to said shaft for raising or lowering the blind and for adjusting the lath into horizontal or inclined position.

5. A Venetian blind as claimed in claim 3 and comprising a casing supporting said operating shaft, a two-part window frame carrying said casing, driving means carried in said window frame, and means for removably connecting said operatingshaft and said driving means.

6. A Venetian blind as claimed in claim 3 and comprising a casing supporting said operating shaft, a two-part window frame carrying said casing, a drive shaft mounted in said frame and coupled with said operating shaft, a tape drum secured to said drive shaft, and a draw tape wound up on said drum, whereby raising and lowering of the blind and adjustment of the position of the laths is obtained by actuation of said tape.

7. A Venetian blind having a rotatable lath operating shaft, a swing frame mounted for pivoting movement on the shaft, a winding drum secured to the shaft, a iiexible pull member depending from the winding drum and extending through the laths and attached to the lowermost lath, lath carrying ladder bands suspended on said swing frame, a pawl and ratchet device operable to turn said swing frames for adjusting the position of the laths, said device including a cam disc mounted for rotation with said operating shaft, said cam disc having on the periphery thereof a projection, a notch and a circular suriaceportion in successive order, a pawl for coaction with said cam disc pivotally mounted on said swing frame, one end of said pawl being heavier than the other end thereof, said heavier end of said pawl coacting with and coupling said pawl to said cam disc upon rotation of the operating shaft and causing said swing frame to turn with the shaft, said pawl upon rapid rotation of said operating shaft jumping over` said notch without becoming engaged with said cam disc, while upon slow` rotation of said shaft, the pawls fall into said notch to be coupled with the cam disc and transmit the movement of rotation of said shaft to said lath carrying swing frame,l an inclined surface positioned in proximity to said cam disc, the lighter end of said pawl coacting with said inclined surface and releasing said pawl from engagementI with the cam disc after a predetermined movement of rotation of said swing frame.

FRITZ GRIESSER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,229,221 Pratt Jan. 21, 1941 2,231,778 Swanson Feb. 11, 1941 2,276,716 Cardona Mar. 17, 1942 2,415,222 Spencer Feb. 4, 1947 

